Single-use hypodermic syringes can have different devices for inhibiting their reuse. Strictly speaking, these safety devices are divided into those intended to inhibit reuse by any user and those designed to hinder an accidental reuse by medical personnel. Syringes having positively retracted needles are mostly designed for use in clinics and other medical institutions as a simple means for hindering an accidental reuse.
A prior art syringe (U.S. pat. No. 5,215,533) has a device for vacuum retraction of the needle that consists of a vacuum seal of the piston and a vacuum seal of a needle holder installed in the syringe barrel. The combination of vacuum seals are intended to insure retraction of the needle after the establishment of a vacuum tight connection between the needle holder and piston. This prior art syringe is complicated and requires the use of special materials for insuring a reliable vacuum coupling. It should be noted that various factors can interfere with the reliable vacuum coupling between the needle holder and piston. In addition, the vacuum seals of the piston and needle take a certain space between the needle receiving part of the syringe barrel and the piston so that a part of an injection fluid will be left over.